Ignition systems



Jun 12, 2 A. B. CHERTOFF ET AL 3,039,021

IGNITION SYSTEMS Filed Dec. 4, 1958 FIG.1 IGNITION SYSTEM 20 10 0| Tana TOR COUPLING Y 56 24 MEANS 5 SWITCHING 26 MEANS ENGINE 12 F|G.4 G 5 r16 68\ 46 66 52 NVVv 64 46 7O\ 52 x 64A o q 64C 645 16 A FIG.3 42A FIG.2 g, 42 42B 4/ l 38 I INVENTORS Allen B. Chgrfoff BY Ian M. Shlvack ATTORNEY United States Patent 3,039,021 IGNITION SYSTEMS Allen B. Chertoil, Brooklyn, and Ian M. Shivack, Flushing, N.Y., assignors to Ultranetic Associates, Inc., Flushing, N.Y., a corporation of New York Filed Dec. 4, 1958, Ser. No. 778,210 12 Claims. (Cl. 315206) This invention relates to ignition systems and more particularly, concerns ignition systems for internal combustion engines.

Automotive engines comprise a plurality of cylinders, each having a piston reciprocating therein, a spark plug, inlet and outlet valves. A combustible mixture of gasoline and air is drawn into the cylinders during the down stroke of the piston and is compressed during the upstroke of said piston. At a critical point during the upstroke of the piston, an electrical voltage is supplied to the spark plug and in ionizing the gap of the plug, a discharge is produced which is of a magnitude and temperature to ignite the combustible mixture.

The explosion that follows, drives the piston down, causing the crank shaft to which the piston is eccentrically connected, to rotate. Waste products of combustion as well as any unignited mixture are exhausted by way of the outlet valve. Linkages responsive to successive angular positions of the crankshaft, synchronize the supply of electrical voltage to the spark plug at proper intervals of time. Thus, there is provided a cam operated current breaker which controls the timing of the voltage supply to the spark plug.

Since internal combustion engines usually comprise multicylinders, a commutating switch in the form of a distributor sequentially couples the current breaker to the spark plugs of the respective cylinders. Mechanical linkages synchronize the operation of the distributor with the rotation of the crankshaft and relate the same to the operation of the current breaker.

With conventional ignition systems, the combustible mixture introduced into the cylinders is never completely ignited and the residual unignited vapors represent a loss of potential power. In addition to such inefficiency in operation, the exhausted waste gases pollute the atmosphere and create sources of contamination and adverse physiological effects, particularly in urban areas.

Accordingly, an object of this invention is to provide an improved ignition system for internal combustion engines which substantially increases their operational efficiency and minimizes unignited gases exhausted from the cylinders thereof.

A further object of this invention is to provide an ignition system wherein each spark plug is energized at least twice during each cycle of operation, thereby insuring ignition of an increased proportion of the combustible mixture introduced into the cylinder.

Since ignition of the vapors of the combustible mixture is caused by an arc across the spark plug gap, a high voltage pulse is required. This is conventionally obtained by interrupting the flow of current through an inductance interposed between the current breaker and the distributor, such inductance being in the form of a transformer, better known as an ignition coil.

The output voltage of the ignition coil is a function of the current flowing through the coil and the rapidity of the change in current. Thus, the output voltage will be greater if the peak current in the coil is greater or it there is a more abrupt change in the current when the breaker is opened.

Unfortunately, the two conditions noted are mutually opposing. The steady state current flowing through the current breaker is very large, being of the order of several amperes. Such a current tends to corrode and pit the contacts or points of the breaker due to constant arcing between the high speed opening and closing; of the con tacts. Such arcing increases the time required for the current to change in the ignition coil and the output voltage supplied to the lugs is decreased.

Accordingly, another object of this invention is to provide an improved ignition system including means for minimizing arcing at the points of the current breaker.

Still another object of this invention is to provide coupling means between the current breaker and the ignition coil, which draws negligible current from the current breaker, and provides sufficiently large currents for the ignition coil. In accordance with this aspect of the invention, such coupling means comprises transistor means suitably connected to the current breaker and ignition coil.

Since current of rather small magnitude, of the order of some thousandths of an ampere, is required at the input terminals of the transistor, various means are available for energizing the spark plugs more than once during each cycle of operation.

Still another object of this invention is to provide an improved ignition system which results in greatly increased useful life of the points or contacts, and more rapid switching time, giving rise to a hotter spark which is not weakened at higher cycling rates.

Other objects will in part be obvious and in part hereinafter pointed out.

In the drawing,

FIG. 1 is a schematic showing of an ignition system for an internal combustion engine, embodying the invention;

FIG. 2 is a schematic representation of switching means for the system of FIG. 1;

FIG. 3 is an alternative form of switching means for the system of FIG. 1;

FIG. 4 is a schematic representation of a coupling means for the system of FIG. 1; and FIG. 5 shows an alternative form of coupling means for the system of FIG. 1.

As shown in FIG. 1, 10 designates an ignition system embodying the invention, for use with an internal combustion engine indicated at 12. The system 10 comprises switching means 14 and serially connected thereto, coupling means 16, a transistor 18, ignition. coil 20 and distributor 22. The engine 12 comprises a plurality of cylinders 24, shown as four in number for the purpose of illustration. Each cylinder 24 has a piston 26 reciprocable therein and connected to a crank shaft, not shown, in a manner known in the art. Each cylinder 24 further includes an inlet valve 30, outlet valve 32 and a spark plug 34 coupled by line 36 to distributor 22.

Mechanical linkages 38, 40, respectively couple switching means 14 and distributor 22 to the crank shaft, to synchronize their operation with the rotation of said crank shaft.

Each cylinder 24 is charged with a combustible mixture of gasoline and air, in a manner known in the art. The associated piston 26 of the cylinder starts its upstroke to compress the mixture and during a major portion of such upstroke, the switching means 14 is open and no current is supplied to transistor 18. However, before the upstroke of piston 26 is completed, switching means 14 momentarily closes and a signal is fed to transistor 18, producing an abrupt rise in the current flowing through the primary winding 20A of ignition coil 20. A voltage is thus created across winding 20A and by transformer action, is transmitted as a stepped-up voltage from the secondary winding 20B, to distributor 22.

At this time, due to synchronized operation of distributor 22, the input to the distributor is coupled to spark plug 34 associated with the cylinder 24 which is undergoing the compression portion of the cycle. The high Voltage supplied to such spark plug 34 ignites the combustible mixture, resulting in an explosion which drives the piston 26 downward to rotate the crank shaft. This action is repeated with the other cylinders in sequential order.

More particularly, in accordance with the invention, switching means 14, indicated in 'FIG. 1, may take the form shown in FIG. 2, wherein a cam operated switch 42 has a fixed contact or point 42A coupled by line 44 to ground potential. The movable contact 42B is coupled by line 46 to the coupling means 16 shown in FIG. 1. A cam 48 operated by linkage 38, drives a cam follower 50 on the support member for contact 42B. The configuration of cam 48 and its relationship to cam follower 50 is such as to insure that contacts 42A, 42B remain open during the major portion of the cycle for each cylinder, and closes at least once during the cycle.

Thus, the voltage on line 46 usually floats but when contacts 42A, 42B close, line 46 is fixed to ground potential. Although coupling means 16 may take various forms, as hereinafter described, such coupling means may be assumed to be a single wire conductor connecting line 46 to a line 52 interconnected to transistor 18. Said transistor 18 is shown as an n-p-n type having a base 18B coupled by way of a base bias resistor 54 to lead 52; an emitter 18A connected to the negative terminal of a battery 56 whose positive terminal is grounded; and a collector 18C coupled to one end of primary winding 20A of ignition coil 20.

Thus, as long as base 183 is not at substantially ground potential, no current flows from ground through primary winding 20A, collector 18C, emitter 18A, to battery 56. However, when base 18B is connected to substantially ground potential, there is an abrupt closing of the circuit between collector 18C and emitter 18A, and current flows in winding 20A. This abrupt change from substantially zero to a peak value of current flow, causes a voltage to be generated across winding 20A.

Although there are several transistors suit-able for use in this system, the selected device should be capable of handling several amperes; the tolerable collector back voltage should be at least in the range of about 6080 volts; and the resistance between emitter and collector should be as small 'as possible, preferably less than 1 ohm. A representative transistor for this purpose is the 2N 173 type manufactured by Delco Division .of General Motors Corp.

In order to minimize the effects of back voltage on transistor 18, it may be desirable to shunt winding 20A with a damping diode 58, as shown in FIG. 1. The damping diode minimizes the restrictions placed on the back voltage requirements of the transistor. While a n-p-n transistor is specifically referrred to herein, it is understood that a p-n-p type transistor may also be used, provided the polarity of the potentials are reversed.

The ignition coil 20 is basically a step-up transformer and the voltage pulse developed across primary Winding 20A due to the switching action of transistor 18, is stepped up in secondary winding 20B, and is supplied by a line 60 to the input terminal of distributor 22.

Distributor 22 is essentially a commutator having a moving contact 122 and a plurality of fixed contacts 222; the contact 122 being connected to line 60. The fixed contacts 222 are connected by lines 36 to the spark plugs 34 in the respective cylinders 24. The mechanical linkage 40 synchronizes the positioning of contact 122 with the rotation of the crank shaft. Thus, contact 122 sequentially connects the contacts 222 to coil 20. This action insures the firing of each spark plug 34 with at least one voltage pulse when the associated cylinder 24 contains a combustible vapor mixture.

However, several voltage pulses may be supplied to the spark plugs 34, to ignite a single charge of combustible vapor in the associated cylinder 24, as indicated by the arrangement shown in FIG. 3. Here is shown a switching means 14' similar to that shown in FIG. 2, except that cam 62 has multi-lobes. Thus, cam 62 has two consecutive lobes assigned to each cylinder 24 whereas in device 14, cam 48 has but a single lobe assigned to each cylinder. Cam 62 makes contact between contacts 42A, 42B twice during the portions of the cycle assigned to the successive cylinders 24.

It should be noted that while the switching means 14, 1-4 as shown in FIGS. 2, 3, have their contacts 42A, 42B normally open and the transistor 18 non-conducting; it is understood that said contacts may be normally closed and transistor 18 may be conducting. In either case, the desired change in current, will take place.

Furthermore, multi-firing may be achieved with switching means 14, when used with a special coupling means shown in FIG. 4 and based on a tank circuit 64. Such circuit comprises a variable capacitor 64A in series with a resistor 6413, which is in parallel with an inductor 64C. One end of tank circuit 64 is connected to the junction of lines 46, 52, while the other end of the circuit is grounded.

The circuit 64 has the property of generating a series of damped oscillations when it is excited by switching means 14. Resistor 64B limits the number of useful oscillations per excitation. The circuit 64 is tuned to a natural resonant frequency that is much higher than the frequency associated with the cycle of engine 12. Since the time of such cycle depends on the rotational speed of the engine, it may be necessary to choose an optimum value of the resonant frequency of circuit 64, .or it may be desirable to employ a variable capacitor which is mechanically linked to the timing advance that is usually incorporated in internal combustion engines.

In FIG. 5 is shown an alternative form of coupling means 16 which comprises essentially two paths 68, 70 in parallel. Such paths 68, 70 couple lines 46 and 52. Path 68 is a direct coupling, i.e., a signal on line 46 is immediately transferred to line 52, while path 70 is a delayed coupling of said lines, i.e., a signal on line 46 is transferred after a time delay, to line 52. Path 70 may comprise a conventional lumped parameter delay line having a delay that is predetermined by the time of the optimum cycle of the engine 12.

There has thus been disclosed, improved ignition systems which markedly increase the efiiciency of internal combustion engines. Such systems provide means for multi-firing the engine cylinders to achieve operational economy and also minimize atmospheric polution. Further, the use of transistors in such systems, substantially increases the useful life of several elements of the system.

As various changes might be made in the several embodiments of the invention herein shown, without departing from the spirit thereof, it is understood that all matter herein shown or described shall be deemed illustrative and not by way of limitation except as set forth in the appended claims.

Having thus disclosed our invention, we claim as new and desire to protect by Letters Patent:

1. In the ignition system of an internal combustion engine, a plurality of spark plugs, and a distributor having a plurality of output terminals respectively coupled to said spank plugs, and input means coupled sequentially to the output means of said distributor, improved means for energizing said spark plugs comprising a source of electrical energy, transistor switching means for coupling said energy source to the input of said distributor, means for synchronizing the operation of said transistor switching means to the operation of said distributor, and means associated with said transistor switching means for supplying at least two pulses of electrical energy from said energy source to the input means of said distributor when said transistor switching means is operative.

2. In the ignition system of an internal combustion engine, a plurality of spark plugs, a distributor having a plurality of output terminals respectively coupled to said spark plugs and input means sequentially coupled to each of said output terminals, improved means for energizing said spark plugs comprising an ignition coil having input and output means, means for coupling the input means of said distributor to the output means of said coil, a source of electrical energy, transistor switching means for coupling said energy source to the input means of said coil, means for synchronizing said transistor switching means with said distributor, and means associated with said transistor switching means for supplying at least two successive pulses of electrical energy from said energy source to the input means of said distributor by way of said ignition coil when said transistor switching means is operative.

3. In the ignition system of an internal combustion engine, a plurality of spark plugs, a distributor having output means respectively coupled to said spark plugs and input means sequentially coupled to said output means, improved means for energizing said spank plugs comprising an ignition coil having primary and secondary windings in inductively coupled relation, means coupling said secondary winding with the input means of said distributor, a source of electrical energy, a transistor having first, second and third terminals, means coupling the first and second transistor terminals, said energy source and the primary winding of said ignition coil in a series circuit, switch means, means coupling said switch means and the third transistor terminal, and means for synchronizing said switch means with said distributor whereby said switch means is operative so that an electrical pulse is transmitted to the input means of said distributor, said switch means being actuated twice during each cycle of operation of the engine.

4. In the ignition system of an internal combustion engine, a plurality of spark plugs, a distributor having output means respectively coupled to said spark plugs and input means sequentially coupled to said output means, improved means for energizing said spark plugs comprising an ignition coil having primary and secondary windings in inductively coupled relation, means coupling said secondary winding with the input means of said distributor, a source of electrical energy, a transistor having first, second and third terminals, means coupling the first and second transistor terminals, said energy source and the primary winding of said ignition coil in a series circuit, switch means, means coupling said switch means and the third transistor terminal, electrical pulse delay means coupling said switch means to the third transistor terminal.

5. In the ignition system for an internal combustion engine, a plurality of spark plugs, a distributor having output means respectively coupled to said spark plugs, and input means that is sequentially coupled to said out put means, improved means for energizing said spark plugs comprising an ignition coil having primary and secondary windings, means for coupling the secondary winding of said coil to the input means of said distributor, a source of electrical energy, a transistor having a base, an emitter and a collector, means for coupling said primary winding, said energy source and the emitter and collector of said transistor in a series circuit, switch means, means for coupling said switch means to the base of said transistor whereby said switch means is activated so that an electrical pulse is transmitted to the distributor input means, said switch means being activated twice during each cycle of operation of the engine.

6. In the ignition system for an internal combustion engine, a plurality of spark plugs, a distributor having output means respectively coupled to said spark plugs, and input means that is sequentially coupled to said output means, improved means for energizing said spark plugs comprising an ignition coil having primary and secondary windings, means for coupling the secondary winding of said coil to the input means of said distributor, a source of electrical energy, a transistor having a base, an emitter and a collector, means for coupling said primary winding, said energy source and the emitter and collector of said transistor in a series circuit, switch means, and means for coupling said switch means to the base of said transistor whereby said switch means is activated so that an electrical pulse is transmitted to the distributor input means, said last mentioned coupling means including pulse delay means for providing a delayed activation of said transistor during each cycle of operation of the engine.

7. In the ignition system for an internal combustion engine, a plurality of spark plugs, a distributor having output means respectively coupled to said spark plugs, and input means that is sequentially coupled to said output means, improved means for energizing said spark plugs comprising an ignition coil having primary and secondary windings, means for coupling the secondary winding of said coil to the input means of said distributor, a source of electrical energy, a transistor having a base, an emitter and collector, means, for coupling said primary Winding, said energy source and the emitter and collector of said transistor in a series circuit, switch means, and means for coupling said switch means to the base of said transistor whereby said switch means is activated so that an electrical pulse is transmitted to the distributor input means, said last mentioned coupling means including an oscillatory circuit operative upon excitation to transmit damped oscillations.

8. In the ignition system for an internal combustion engine, a plurality of spark plugs, a distributor having output means respectively coupled to said spark plugs, and input means that is sequentially coupled to said output means, improved means for energizing said spark plugs comprising an ignition coil having primary and secondary windings, means for coupling the secondary winding of said coil to the input means of said distributor, a source of electrical energy, a transistor having a base, an emitter and collector, means for coupling said primary winding, said energy source and the emitter and collector of said transistor in a series circuit, switch means, and means for coupling said switch means to the base of said transistor whereby said switch means is activated so that an electrical pulse is transmitted to the distributor input means, said last mentioned coupling means including direct coupling means and pulse delay means in parallel with said direct coupling means whereby said transistor is energized twice when said switch means is activated.

9. In the ignition system of an internal combustion engine, a plurality of spark plugs, a distributor having a plurality of output means respectively coupled with said spark plugs and input means sequentially coupled to said output means, improved means for energizing said spark plugs comprising an ignition coil having primary and secondary windings, means for coupling said secondary winding to the distributor input means, means for grounding one end of said primary winding, a source of electrical energy, a transistor having a base, an emitter and a collector, means for coupling said collector to the other end of said primary winding, means for coupling said emitter to said energy source, switch means having input and output means, means for coupling the switch input means to ground, means for coupling the switch output means to said base, and means for synchronizing the operation of said switch means with said distributor whereby said switch means is operative so that an electrical pulse is transmitted to the input means of said distributor, said switch means being actuated at least twice during each cycle of operation of the engine.

10. In the ignition system of an internal combustion engine, a plurality of spark plugs, a distributor having a plurality of output means respectively coupled with said spark plugs and input means sequentially coupled to said output means, improved means for energizing said spark plugs comprising an ignition coil having primary and secondary windings, means for coupling said secondary winding to the distributor input means, means for grounding one end of said primary winding, a source of electrical energy, a transistor having a base, an emitter and a collector, means for coupling said collector to the other end of said primary winding, means for coupling said smitter to said energy source, switch means having input and output means, means for coupling the switch input means to ground, means for coupling the switch output means to said base, and means for synchronizing the operation of said switch means with said distributor whereby said switch means is operative so that an electrical pulse is transmitted to the input means of said distrtibutor, said last means coupling means including pulse delay means for providing a delayed activation of said transistor during each cycle of operation of the engine.

11. In the ignition system of an internal combustion engine, a plurality of spark plugs, a distributor having a plurality of output means respectively coupled to said spark plugs and input means sequentially coupled to said output means, improved means for energizing said spark plugs comprising an ignition coil having primary and secondary windings, means for coupling said secondary winding to the distributor input means, means for grounding one end of said primary winding, a source of electrical energy, a transistor having a base, an emitter and a collector, means for coupling said collector to the other end of said primary winding, means for coupling said emitter to said energy source, switch means having input and output means, means for coupling the switch input means to ground, means for coupling the switch output means to said base, and means for synchronizing the operation of said switch means with said distributor whereby said switch means is operative so that an electrical pulse is transmitted to the input means of said distributor, said last mentioned coupling means including an oscillatory circuit which is operative when excited to transmit damped oscillations to the base of said transistor.

12. In the ignition system of an internal combustion engine, a plurality of spark plugs, a distributor having a plurality of output means respectively coupled with said spark plugs and input means sequentially coupled to said output means, improved means for energizing said spark plugs comprising an ignition coil having primary and secondary windings, means for coupling said secondary Winding to the distributor input means, means for grounding one end of said primary winding, a source of electrical energy, a transistor having a base, an emitter and a collector, means for coupling said collector to the other end of said primary Winding, means for coupling said emitter to said energy source, switch means having input and output means, means for coupling the switch input means to ground, means for coupling the switch output means to said base, and means for synchronizing the operation of said switch means With said distributor whereby said switch means is operative so that an electrical pulse is transmitted to the input means of said distributor, said last mentioned coupling means including direct coupling means and pulse delay means in parallel with said direct coupling means whereby to energize said transistor twice when said switch means is activated.

References Cited in the file of this patent UNITED STATES PATENTS 2,003,466 Randolf June 4, 1936 2,066,959 Cain Jan. 5, 1937 2,427,247 Wilkinson Sept. 9, 1947 2,433,462 Laird Dec. 30, 1947 2,497,307 Lang Feb. 14, 1950 2,584,507 Smits Feb. 5, 1952 2,852,588 Hartman Sept. 16, 1958 2,852,589 Johnson Sept. 16, 1958 2,878,298 Giacoletto Mar. 17, 1959 FOREIGN PATENTS 1,137,949 France Jan. 21, 1957 

